Analysis Of Electromagnetic Characteristics Research Articles

Electromagnetic design and performance analysis of large-scale offshore wind generators with modular fractional-slot concentrated winding

Future offshore wind engineering raises demands on higher reliability, better power generating performance, as well as lower manufacturing and transportation cost. This paper presents a direct-driven permanent magnet generator (DDPMG) with modular fractional-slot concentrated winding (MFSCW), to meet the large-scale, low-cost and high-reliability requirements of offshore wind power applications. The corresponding pole–slot combination method and electromagnetic characteristics analysis for this novel generator are proposed and performed in detail, including the winding coefficient analysis, magnetomotive force (MMF) harmonic analysis, cogging torque analysis, finite element simulations and generator parameter optimization. After finite element simulations, a 3.3 MW prototype MFSCW-DDPMG is developed to validate the proposed scheme. The results provide a complete and feasible scheme of pole–slot​ combination and electromagnetic design for future MFSCW-DDPMG engineering applications.

Research on strain testing technology of electromagnetic railgun’s abnormal barrel

Aiming at difficult strain test and unable to accurate strain test for electromagnetic railgun’s special-shaped barrel bore, the strain testing technology of special-shaped barrel was studied. According to electromagnetic railgun strain test characteristics analysis, the back of the rail and the back of insulation support plate are selected as the strain test points, FBG(Fiber Bragg Grating) stain sensor is embedded along the circumference of the barrel to obtain the special-shaped barrel true stain value. At the same time, in order to comparison, The papers studies the rail’s strain simulation technology for electromagnetic railgun, the simulation result is accordance with strain test result, show that stain measurement method is feasible, and measurement results is reliable. The research results can provide data support for location to position of projectile in the special-shaped barrel bore by strain feature.

Analysis of Electromagnetic Characteristics of 6.5 MVA/25 kV HTS Traction Transformer Using T–A Formulation

Low AC loss of the winding of high-capacity high temperature superconducting (HTS) traction transformer is a very important link to introduce large capacity traction transformer into commercialization. A new winding structure is proposed for the transformer. The HV windings are made of double pancake coils (DPCs), which are wound by 4.8 mm-wide tapes, and the LV windings, which are wound by 12 mm-wide tapes, are solenoid coils. The electromagnetic characteristics of the new winding structure of the traction transformer are analyzed by <i>H</i>-formulation homogenization method and <i>T</i>-<i>A</i> formulation homogenization method respectively. Significant HTS tape cost reduction could be achieved without compromising AC loss by using hybrid windings into the new winding structure. We report that the <i>H</i>-formulation homogenization model and <i>T</i>-<i>A</i> formulation homogenization model are used to calculate the AC loss of the new winding structure with flux diverters (FDs) at the end. The results meet the design requirements of less than 2 kW, which shows the feasibility of the new winding structure. Due to the good convergence of <i>H</i>-formulation and poor convergence of <i>T</i>-<i>A</i> formulation under the homogenization model of the transformer, no one has used <i>T</i>-<i>A</i> formulation to calculate the electromagnetic characteristics of the transformer before. Due to the simplicity of <i>T</i>-<i>A</i> formulation applied to large-scale superconducting system, a new form of mesh generation is proposed to improve the convergence and accuracy of <i>T</i>-<i>A</i> formulation homogenization model calculation of the transformer in this paper. This paper verifies the correctness of the calculation of HTS transformer by <i>T</i>-<i>A</i> formulation, and provides a reference for the application of <i>T</i>-<i>A</i> formulation in more superconducting fields

Improving the Energy Efficiency of a Ship’s Power Plant by Using an Autonomous Hybrid System with a PMSG

In ship systems, diesel power generators are used in various systems of autonomous power plants to ensure power supply security. This article presents an autonomous hybrid system of a ship power plant with a diesel generator with a permanent magnet synchronous generator and electricity storage in parallel topology (the permanent magnet synchronous generator is connected directly to the receiving network). The electricity storage through the active converter is connected to the receiving network in parallel with the permanent magnet synchronous generator. The decoupled control of the reactive and active power in the active converter enables stabilization of the voltage in the ship’s electrical power grid while ensuring the possibility of obtaining different operating regimes of the power plant at various stages of the ship’s operation. The innovative method of voltage stabilization presented in this article is based on the compensation of the unfavorable reaction of the permanent magnet synchronous generator armature through the optimal transmission of negative inductive reactive power from the active converter to the generator using the electromagnetic properties of the synchronous generator. The active converter controls the direction of the active power transmission between the DC source, the grid, and the permanent magnet synchronous generator. This paper proposes a hybrid autonomous power plant system using battery storage in place of a single diesel generator set against the commonly used two diesel generator sets, working in parallel, to increase the energy efficiency of the power plant by minimizing the specific fuel consumption of the diesel generator set. The article examines the possibilities of such a mechatronic system design based on analytical research and analysis of electromagnetic and energy characteristics using the Matlab-Simulink program.

Analysis of electromagnetic characteristics of typical faults in permanent magnet wind generators

Due to the harsh actual operating environment of the permanent magnet wind turbine, it is easy to break down and difficult to monitor. Therefore, the electromagnetic characteristics identification of major fault types of large-scale permanent magnet wind turbines is studied in this paper. The typical faults of rotor eccentricity, stator winding short circuit and permanent magnet demagnetization of permanent magnet wind turbines are analyzed theoretically. The wavelet analysis algorithm is used to decompose and reconstruct the abnormal electromagnetic signal waveform band, and the characteristic frequency of the electromagnetic signal is obtained when the fault occurs. In order to verify the effectiveness of the proposed method, a 3.680MW permanent magnet wind turbine was taken as the research object. Its physical simulation model was established, and an external circuit was built to carry out field co-simulation. The results show that the motor fault type can be determined by detecting the change rule of fault characteristic frequency in the spectrum diagram, and the electromagnetic characteristic analysis can be applied to the early monitoring of the permanent magnet wind turbine fault.

Computational characterisation of microwave heating of fibre preforms for CVI of SiCf/SiC composites

Silicon carbide fibre reinforced silicon carbide matrix composites (SiCf/SiC) are known as materials with high-performance mechanical properties for the aerospace industry. Microwave-enhanced (ME) chemical vapour infiltration (CVI) heating of ceramic matrix composites is potentially an energy efficient production technique capable of yielding near fully dense SiCf/SiC composites in a much shorter time span. This paper reports on the output of computational analysis of electromagnetic (EM) and thermal characteristics of the ME CVI process occurring with thin circular SiC fibre preform in a Labotron microwave system from SAIREM. Computer simulation is performed with the use of the finite-difference time-domain technique implemented in QuickWave computational environment. Multiple puzzling phenomena observed in the earlier experimental work are illuminated in the present study and the causes for the formation of microwave-induced temperature fields are clarified. With the use of the developed EM model, resonant and non-resonant frequencies of the Labotron system for different temperatures of the processed samples are analysed to explain the differences and variability in heating rates. This showed that when microwave processing of small SiC samples, energy coupling is extremely sensitive to frequency: a change of the reflection coefficient from 0.05 (absorbing) to 0.75 (reflective) could be made by a drift as small as 0.003–0.005 GHz, respectively, indicating the importance of scaling the microwave cavity to the sample size and the ability to precisely control the frequency of the microwave source. Moreover, energy coupling is temperature-dependent: low reflections produces very high heating rates (greater than 550 ℃ min-1); the opposite is true for high reflections where heating rates are significantly slower. Temperature fields in the SiC fibre preforms are computed with the coupled EM-thermal model at different frequencies. It is shown that while being highly non-uniform in the beginning of the process, temperature patterns evolve to being fairly homogeneous by its end. Overall, the results suggest a means for better control of the equipment to pave the way to more efficient, controlled, and repeatable implementations of the ME CVI technology to produce high quality SiCf/SiC composites.

Analysis of Electromagnetic–Mechanical Characteristics according to Shaft Materials of Permanent Magnet Synchronous Motor

In this paper, an analysis of electromagnetic–mechanical characteristics according to the shaft materials of a permanent magnet synchronous motor was performed. In general, the shaft of an electric motor rotating at high speed uses various materials, considering the mechanical rigidity and electromagnetic characteristics. However, because the material of the shaft has a significant influence on the electromagnetic performance according to the characteristics of the non-magnetic and magnetic materials, electromagnetic characteristics analysis was performed according to the material of the shaft. In addition, because the machine rotating at a high speed entails mechanical problems owing to the centrifugal force, the mechanical stability was secured through critical speed characteristic analysis according to each material after performing the von Mises stress analysis of the permanent magnet and sleeve.

Electromagnetic Characteristics Analysis and Structure Optimization of High-Speed Fuel Solenoid Valves

High-speed fuel solenoid valves (HFSVs) are the key control elements of aero-engine vane regulators. A strong electromagnetic force generated from the HFSVs is essential to achieve precise control over timing and quantification for fuel supply. In this paper, the Taguchi method is adopted to improve the HFSV’s static electromagnetic characteristics. First, an electromagnetic model of the HFSV was established and experiments were conducted to modify and validate the model. Effects of key structural factors on the static electromagnetic characteristics of the HFSV are then investigated via the finite element method (FEM). Based on the optimization, an HFSV prototype is finally manufactured and tested. The experiment results are in good agreement with those of the simulations. It provides a significant guideline for the manufacturing process of such HFSVs.

Retracted: Electromagnetic Characteristics Analysis of Superconducting Electrodynamic Suspension System With Rolling Transient Condition

The curved track or uneven side wall has a great impact on the stable running of high-speed electric superconducting (SC) suspension system. The change of electromechanical performances of SC linear synchronous motor (LSM) with rolling transient condition is an important research topic. A novel and comprehensive double-Fourier analysis method is proposed, to analysis the forces and stiffness characteristics of coreless-type SC LSM (SC-LSM) under the rolling transient posture. Primary, the motor topological and rolling posture performance of the SC-LSM are proposed. Following, the 3-D analytical representation of forces and stiffness are acquired by compound circuit of primary current and Fourier analysis of secondary field, contain suspension performance, guidance performance, rolling torque and stiffness, propulsion and magnetic drag force, time-domain electromagnetic forces, etc. Third, the forces and stiffness performance on one SC-LSM is calculated with various horizontal deviation and rolling transient postures of maglev train through the novel analytical model and finite-element model. Finally, the rationality on the 3-D analytical method is proved though the experimental test value.

Modeling and Analysis of Radial Electromagnetic Force and Vibration Characteristics Based on Deflection Dual-Stator Switched Reluctance Generator.

In this paper, a mechanical model of the deflection dual-stator switched reluctance generator (DDSRG) is developed, and the advantages of the dual-stator structure for the deflecting motion are analyzed. Secondly, the spatio-temporal and spatial distribution characteristics of the inhomogeneous electromagnetic force are derived analytically and further verified by fast Fourier transform (FFT).Thirdly, the spatial and temporal distributions of electromagnetic forces of DDSRG are calculated based on finite element software, and the distributions of electromagnetic forces under different motion states are analyzed. By combining the analysis of modal analysis and harmonic response analysis, the free mode and vibration response acceleration variation laws of the internal and external stator are determined. The results show that the order of electromagnetic forces on the stator at rated speed is mainly 8 times the fundamental frequency, and the modal vibration order is more violent in the order of 2–7. Finally, the experimental platform of DDSRG is built, and the vibration characteristics are tested to verify the validity and accuracy of the proposed simulation results.

Comparative Study of NVH of Permanent Magnet Machines According to Rotor Eccentricity With Fractional Pole/Slot Combinations

In this study, to analyze the effects of electromagnetic factors that are affected by the eccentricity on vibration, an overall structural model of a motor was constructed, including the stator core, rotor structure, and the other parts. Thereafter, a mode analysis was performed to verify the dynamic stiffness of the constructed model using the finite element method. Vibration analysis was performed using a method that applied the electromagnetic characteristic analysis results to the mechanical system using the finite element model of the entire mechanical system, and the analysis results were obtained. To verify the validity of the proposed analysis method, a comparison of the test results obtained from the finite element analysis and fabrication model was performed. Finally, by analyzing the effect of changes in the electromagnetic characteristics due to eccentricity on vibration, it was confirmed that the change in electromagnetic characteristics was reflected in the vibration characteristics. In addition, the trend followed by the vibration characteristics derived from the analysis results agreed well with the measured vibration tendency, indicating that the vibration analysis could be performed by the method presented in this paper.

Electromagnetic Characteristics Analysis of Quadrupole Compound Orbital Electromagnetic Launcher with Different Configurations

During the operation of the Quadrupole Compound Orbital electromagnetic launcher, the current is easy to gather in the armature and the rail contact surface. Serious turn and arc ablation can occur, causing damage to the rail and the armature and affecting the life of the launcher. To better solve the thermal ablation problem of the armature and the rail, three different configurations of the rail and the armature are established, and the current density, magnetic field distribution and electromagnetic force of the rail and the armature are compared and analyzed using the finite element method, and the effect of concave and convex values of the armature rail on current distribution and electromagnetic force is discussed. The results show that the planar armature can effectively reduce the maximum current density and mitigate thermal damage. The concave elliptical rail produces the largest electromagnetic thrust and the smallest radial electromagnetic force, and the armature is more stable during firing. The maximum current density and magnetic field strength are negatively correlated with the concave and convex values; the electromagnetic thrust applied to the concave elliptical armature is negatively correlated with the concave value, while the electromagnetic force applied to the convex elliptical armature is positively correlated with the convex value.

Research on the inverse vector hysteresis model with the deep learning parameter identification algorithm

The construction of the vector hysteresis model is significant for the electromagnetic characteristics analysis of electrical equipment. With a deep learning parameter identification algorithm, this paper presents a modeling method of the inverse vector hysteresis model. The vector Everett function is obtained by the alternating hysteresis data. In order to reduce the error of the vector Everett function, the anisotropy compensation coefficient is introduced into the model structure. Based on the white-box model theory, the Stacked Auto-Encoder (SAE) model is used to identify the relevant parameters of the inverse vector hysteresis model. And the parameters of the phase angle compensation function are calculated by the magnetic loss data to further improve the magnetic loss calculation accuracy of the vector model. Compared with the experimental data of rotating magnetization, the fitting result proves the accuracy of the model in a wide range. In addition, the validity of the model is verified by calculating the dynamic magnetic loss.

Electromagnetic Characteristics Analysis in Double‐Sided Permanent Magnet Linear Synchronous Motor with Asymmetrical Air‐Gap

The double‐sided permanent magnet linear synchronous motor (DS‐PMLSM) is widely used in the industrial field with high precision and long strokes due to simple construction, high instantaneous thrust and high controllability. However, parasitic issues, such as unavoidable manufacturing tolerances, might cause the symmetrical position deviation of primary or secondary components, which results in an asymmetrical air‐gap between components, affecting the motor's electromagnetic characteristics further. In this paper, it is taken into account secondary torsional or offset conditions (the secondary component is displaced sideways from a symmetrical position), and investigates the variations of electromagnetic characteristics on the 12‐solt 14‐pole short‐primary DS‐PMLSM. Based on the finite element method (FEM), the effects of secondary torsion or offset on the air‐gap flux density, the back‐EMF, the detent force, the thrust force, and the normal force are investigated and compared respectively. In addition, the analytical results of the back‐EMF considering lower secondary torsion are verified on a lower secondary torsional prototype. From the analytical results of electromagnetic characteristics, it is revealed that with the torsional angle or offset distance rising, the normal force and detent force in the Y‐axis gradually increase, while the thrust force and the back‐EMF decrease. These theoretical researches can play an important role in the operation and assembly process of the DS‐PMLSM. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Analysis of Electromagnetic Transient Characteristics on the Winding of UHVDC Converter Transformers Based on an Improved Broadband Model

This work proposes an improved broadband equivalent circuit model of the winding system of an ultrahigh-voltage direct current (UHVDC) converter transformer and the validation experiment of the model conducted on a tapped transformer. The matrices of the inductance, capacitance, and resistance parameters in the improved model were all obtained by the finite element method according to the winding system structure of a UHVDC transformer. Then, the potential distributions along the windings under impulse voltages with different waveforms were studied in detail. Finally, the relationship between the potential gradient and waveforms was obtained. This work provides a convenient method to acquire the broadband electromagnetic transient characteristics of the winding systems within UHVDC converter transformers.

Microwave waveguide polarizer for satellite communication antennas with circular polarization

The volumes of information transmitted in modern satellite telecommunication systems are constantly increasing. Antennas with signal polarization processing, which is performed by polarizers, are the fundamental elements of such systems. Therefore, the development of methods for the analysis of new polarizers is an important problem. From a technological point of view, polarizers based on waveguides with irises are the simplest. Analysis and optimization of electromagnetic characteristics of a polarizer based on a square waveguide with irises are the goals of the presented research. To solve this optimization problem, we have created a new mathematical model, which allows investigating the influence of the design parameters of the polarizer on its electromagnetic characteristics. A mathematical model of the waveguide polarizer with irises was created by the method of decomposition using wave transmission and scattering matrices. Besides, the new mathematical model takes into account the thickness of the irises using their equivalent T- and П-shaped substitution circuits. The general wave scattering matrix is the basis of a new mathematical model of a waveguide polarizer. This matrix was determined using the theory of microwave circuits. The main characteristics of the waveguide polarizer were determined through the elements of this matrix. Here, we perform the optimization of the polarizer characteristics in the Ku-band 10.7–12.8 GHz. The developed new mathematical model of a waveguide polarizer with irises makes it possible to take into account the heights of the irises, distances between them and their thickness. The new mathematical model determines the electromagnetic characteristics of the polarizer in a simpler and faster way compared to the finite integration technique, which is often used for the analysis of microwave devices for various purposes

Analysis of Electromagnetic Characteristics of a Novel Toroidal Acceleration Linear Motor

A high thrust density linear motor, which adopts a novel toroidal structure, applying to load acceleration in confined space is proposed. The basic structure of the toroidal acceleration permanent magnet synchronous linear motor (TA-PMLSM) is depicted, both with its parameters listed. The main characteristics such as air gap magnetic density and electromagnetic thrust are discussed by establishing the electromagnetic field equation in the cylindrical coordinate system. And simulation comparison between the Halbach permanent magnet array and the classical radial one is also made to get a higher density of the magnetic and electromagnetic thrust. Compared with the conventional radial permanent magnet array, results show that the amplitude of back EMF of ring motor under the action of Halbach permanent magnet array has a better sinusoidal, the magnetic density of the air gap increases by 1.3 times, the thrust density increases by 1.42 times, and the main harmonic content of the two referred physical quantity decreases significantly.

Analysis of electromagnetic transmission characteristics of square loop frequency selective fabrics with different layers

Nine square loop frequency selective fabrics (FSFs) with different layers were designed, prepared, and tested in this paper. Then the electromagnetic transmission characteristics were analyzed in detail. The test results reveal that the transmission characteristics of single-layer FSFs are basically identical in two electromagnetic wave polarization modes and keep good frequency selective characteristics as the incidence angle increases. For FSFs with the same frequency selective surface (FSS) layers, the increase of FSS layer number may exert influence on the electromagnetic transmission characteristics, but the influence mode and extent are inconsistent for two kinds of FSFs. For FSFs with complementary FSS layers, the transmission coefficient curves of the double-layer sample are the combination of two single-layer FSFs, with three resonance phenomena at 7.63, 10.75, and 12.38 GHz. However, three-layer FSFs with complementary FSS layers show poor frequency selective characteristics, mainly presenting full shielding characteristics. An equivalent circuit model of multi-layer FSF is built to explore the electromagnetic transmission mechanism; many factors, such as the fabric type, structure, conductive unit type, and size, would nonlinearly affect the electromagnetic transmission characteristics. The work can provide reference value for the study of diverse multi-layer FSFs and variant electromagnetic characteristics.

Analysis of electromagnetic characteristics of the proposed composite four-rail electromagnetic launcher

Abstract In the existing composite four-rail electromagnetic launcher (CFREL), the armature and rail contact surface produces significant heat and bears considerable wear, thereby reducing the potential amount of electromagnetic thrust to be generated. To eliminate the damage caused by the thermal effect of the rail contact surface and to meet the electromagnetic thrust demand of the load, a CFREL is proposed. The proposed CFREL model is constructed, and the launcher’s electromagnetic characteristics are simulated and compared using the finite element method. The current density, distribution of magnetic flux density, and electromagnetic thrust characteristics are analysed. The results showed that the proposed CFREL reduced the maximum current density of the contact surface and effectively eliminated the current concentration of the armature and rail contact surfaces. Effective magnetic field shielding is realised with a larger range, which can better meet the requirements of the intelligent load’s magnetic field environment and provide stronger electromagnetic thrust for the load, hence solving the problem of insufficient thrust.

Electromagnetic characteristic analysis of a REBCO magnet with a current bypass/distribution winding technique under an asynchronous rotating magnetic field

Generally, high-temperature superconducting rotating machines (HTSRMs) are considered synchronous machines. If the output of the HTSRM fluctuates based on frequent changes in the electrical or mechanical loads, there is the concern that an asynchronous rotating magnetic field (RMF) is applied from the stationary copper armature winding to the high-temperature superconducting (HTS) field winding in the rotary. This may act as a magnetic disturbance to the HTS field magnet, resulting in permanent damage. To enhance the reliability of HTS magnets in wind power and electric propulsion applications, winding methods with current bypass/distribution characteristics, such as no-insulation (NI) and metal-insulation (MI), have attracted scholarly attention because of their high thermal and electrical stabilities, resulting in their self-stabilizing and protective performances. To verify the feasibility of the NI and MI winding techniques for wind power generators, the basic characteristics under a time-varying magnetic field must be studied, contrary to HTS magnet applications under a time-static magnetic field. Therefore, the electromagnetic characteristics of rare-earth barium copper oxide (REBCO) magnets applied with NI and MI winding technologies were compared and analyzed in this study, considering the magnetically transient situations in which an asynchronous RMF is applied to REBCO magnets. In addition, we developed a characteristic evaluation device similar to a synchronous rotating machine to generate the unsynchronized RMF. Moreover, various basic tests were performed to target the small racetrack-type field windings. The critical current, n-value, terminal voltage, and center magnetic field are investigated under various values of the frequency and current amplitude of the three-phase armature winding, and their behaviors are discussed in detail based on the characteristic resistances of the two test magnets.